CD28 and neoplasm: No significant correlation could be found between the degree of CD28 expression and tumor size, histological type, hormone receptor status, DNA ploidy status, Elston histological grade, S-phase, patient age, nodal status or tumor stage following the TNM classification of malignant tumors, neither were there any significant correlation detected regarding clinical data and the degree of CD3-ζ expression in our previously published material [21].